The present invention relates to a method of leveling an existing concrete slab which has had portions settle into the ground so as to become uneven over time. More specifically, to a method of carefully raising a section of the sunken slab so as not to damage the section and allow for the injection of pressurized mason's sand into the cavity created between the bottom of the uneven slab and the settled ground.
Regardless of the care and skill used in the initial construction, concrete slabs tend to become misaligned over time due to different rates of settlement of the earth. Uplift from freeze/thaw cycles or tree root lifting are also common causes of slab misalignment. These problems cause cracks in the slab to develop and can also cause step-like structures to occur between sections of the slab. The end result of this condition is the creation of hazards to users and liability for those who are responsible for their care. Additionally, the uneven slabs are extremely difficult to clear of snow and ice during the winter months in the northern areas of the United States, thus creating further hazards and liabilities for their users and owners.
In the past, there was a number of ways these problems were solved. One of these was to completely remove the damaged section of the slab and then re-pour it. The problem with this method is that although it works very well, it is time consuming and very expensive. The re-pour method also results in a checkerboard looking slab as the new portions are often a very different color from the older weathered sections. Another method that has been used with the step formation problem is to construct concrete or tar ramps from the lower section of the slab to the upper. The problem with this method is that it still leaves uneven slab surfaces that are hazardous and difficult to maintain.
Finally, another method that is often used is mud jacking. In this repair method a hole is drilled through the uneven slab and wet mud is pumped under the slab until the slab becomes level. The main problem with this method is that it may be difficult to effectively level a slab as the mud will settle over time while drying.
Therefore, from the foregoing discussion it can be clearly seen that it would be desirable to provide a means of leveling existing large slabs in an inexpensive manner that is easily used.